President Trump’s plan to hike import tariffs on steel and aluminum rattled American trading partners from Australia to Mexico Friday, risking an all-out trade war with some of the United States's closest allies.

The White House accuses other nations of improperly subsidizing exports in violation of free-trade commitments, a claim they deny. To remedy this perceived transgression, Trump wants to slap a new 25% import tariff on foreign steel, and 10% on aluminum.

The president has already approved two new import tariffs on washing machines and solar energy cells and panels — a move intended to aid U.S. manufacturers.

"When a country (USA) is losing many billions of dollars on trade with virtually every country it does business with, trade wars are good, and easy to win," Trump tweeted Friday.

The claims made by Trump are worth further scrutiny.

How much is the U.S. losing on trade?

The U.S. trade deficit in goods and services exchanged with foreign countries soared 12% to $566 billion last year, according to the U.S. Commerce Department.

That's the highest level since 2008. A trade deficit is typically defined as the amount by which the cost of a country's imports exceeds the value of its exports.

With China, the deficit rose 8% to $375 billion. It was also up against Mexico ($71 billion) and Canada ($18 billion). These three countries are the USA's largest trading partners that are individual nations. The U.S. has a deficit of about $150 billion with the 28-member European Union, according to EU statistics.

Fact Check: On this point, Trump's assertion is accurate as it applies to the U.S. trade deficit.

Are trade wars good?

The U.S. applied an average import tariff of 3.48% in 2016, across all product types from cars to champagne, according to the World Trade Organization (WTO).

Mexico's was 7.01%, China's 9.92% and Canada's 4.08%.

The Brookings Institution economist Dany Bahar pointed out that it's important to remember this is just the maximum tariff these countries promise to apply on imports from other WTO members – across all industries.

"For other nations that the U.S. has a free-trade agreement, such as Canada and Mexico through NAFTA, tariffs are typically lower and in some cases, zero," he wrote in a blog post on the Washington-based think tank's website in January.

"Raising import tariffs is a bad idea," Bahar added. "Not only will it not protect the American worker, it will strongly hurt the American consumer. ... If imports turn out to be more expensive than before, it is the American consumers, and no one else, who will have to pay for that."

Bahar added that imposing tariffs do not necessarily protect American workers.

"Other countries could decide to retaliate by increasing their own import tariffs, putting American jobs in jeopardy," Bahar said. "This is highly critical to consider, as most of the countries that export to the U.S. also import from the U.S."

Fact check: Trump has vowed to renegotiate NAFTA. Imposing new tariffs on steel and aluminum could complicate that as both Canada and Mexico are major exporters of metals to America Trade wars, like all wars, are bad.

Are trade wars easy to win?

International reaction points to a big No on this front.

The European Commission, the EU's executive arm, warned Friday that it would "react firmly" and said it's considering imposing countermeasures against U.S. imports.

"The EU has been a close security ally of the U.S. for decades. We will not sit idly while our industry is hit with unfair measures that put thousands of European jobs at risk," European Commission President Jean-Claude Juncker said.

China's Commerce Ministry did not say whether it would take action, but "expresses grave concern" at the development.

Chrystia Freeland, Canada's foreign minister, said "Canada (would) take responsive measures to defend its trade interests and workers." She referred to any new U.S. tariffs on its steel and aluminum as "absolutely unacceptable."

Brazil, a major exporter of steel to the U.S., expressed "enormous" concern.

Australia said it would "distort trade" and lead to job losses.

And Mexican government sources told the Financial Times that it amounted to a declaration of war in which "Mexico will have no other option than to react."

Fact check: So, are trade wars easy to win? The short answer is no.

Who is the most protectionist of all?

According to a recent study by Gowling WLG, a British law firm that specializes in international trade issues, since 2009 the U.S. passed 1,297 economic or trade measures Gowling WLG deemed to be "harmful" or trade protectionist in nature.

That's about double the amount passed by India over the same period, which came in second. China passed a few hundred. Canada and Mexico don't feature in the top 20.

Fact check: Trump has consistently complained about "unfair" international trade practices. Yet according to Gowling WLG's study, over the last decade the U.S. has in fact been more trade protectionist than an other country.